Fan filter unit and a clean room for using the same

Abstract

A fan filter unit is provided for use in filtering air circulating in a clean room. The fan filter unit includes a unit casing; a ventilation fan housed in the unit casing; a dust removal filter in the bottom of the unit casing; and one or more gas absorption filters for removing gases from the circulating air. The one or more gas absorption filters are located in the unit casing such that the ventilation fan can be inspected without removing the one or more gas absorption filters and an inspector can walk on an upper face of the unit casing. In one preferred embodiment, the one or more gas absorption filters are located above the dust removal filter and below the ventilation fan. In a second preferred embodiment, a fan filter unit is provided that includes a plurality of fan filter subunits, each fan filter subunit comprising a unit casing, a ventilation fan housed in the unit casing, and a dust removal filter in the bottom of the unit casing. The fan filter unit also includes a chamber enclosing the intake sides of the plurality of fan filter subunits, the chamber containing one or more air intake openings in the sides of the chamber. The fan filter unit also includes one or more gas absorption filters for removing gases from the air disposed in the one or more air intake openings of the chamber.

I claim: 
     
       1. A fan filter unit for use in filtering air circulating in a clean room, the fan filter unit comprising: a unit casing having a top and a bottom;   a ventilation fan housed in said unit casing;   a dust removal filter in said bottom of said unit casing;   one or more gas absorption filters located in said casing between said fan and said dust removal filter for removing gases from said circulating air; and   at least one opening in an upper face of said unit casing for permitting inspection of at least one of said fan and said one or more gas absorption filters without disassembling said unit casing.   
     
     
       2. A fan filter unit for use in filtering air circulating in a clean room, the fan filter unit comprising: a unit casing having a top and a bottom;   a ventilation fan housed in said unit casing;   a dust removal filter in said bottom of said unit casing;   one or more gas absorption filters for removing gases from said circulating air, said one or more gas absorption filters being above said dust removal filter and below said ventilation fan; and   at least one opening in an upper face of said unit casing for replacing said one or more gas absorption filters without removing said dust removal filter.   
     
     
       3. The fan filter unit according to claim 2, wherein each of said one or more gas absorption filters is selected from the group consisting of an alkaline gas absorption filter, an acidic gas absorption filter, and an organic gas absorption filter. 
     
     
       4. A fan filter unit for use in filtering air circulating in a clean room, the fan filter unit comprising: a unit casing;   a ventilation fan housed in said unit casing;   a dust removal filter in the bottom of said unit casing:   one or more gas absorption filters for removing gases from said circulating air, said one or more gas absorption filters being above said dust removal filter and below said ventilation fan;   an air intake for said ventilation fan located in an upper face of said unit casing;   inspection openings located in said upper face of said unit casing for removing said one or more gas absorption filters from said unit casing and for inserting said one or more gas absorption filters into said unit casing; and   covers for said inspection openings.   
     
     
       5. The fan filter unit according to claim 4, wherein said one or more gas absorption filters are placed side by side on said dust removal filter, said inspection openings are separated by said air intake for said ventilation fan, and the number, size, and location of said inspection openings correspond to the number, size, and location of said one or more gas absorption filters. 
     
     
       6. A vertical laminar-flow type clean room, comprising: one or more work areas;   a circulation system for circulating air downwardly through the clean room;   one or more fan filter units located above the one or more work areas, each fan filter unit comprising: a unit casing having a top and a bottom;   a ventilation fan housed in said unit casing;   a dust removal filter in said bottom of said unit casing;   one or more gas absorption filters for removing gases from said circulating air, said one or more gas absorption filters being above said dust removal filter and below said ventilation fan; and   at least one opening in an upper face of said unit casing for replacing said one or more gas absorption filters without removing said dust removal filter.     
     
     
       7. The clean room according to claim 6, wherein each of said one or more gas absorption filters is selected from the group consisting of an alkaline gas absorption filter, an acidic gas absorption filter, and an organic gas absorption filter. 
     
     
       8. A vertical laminar-flow type clean room comprising: one or more work areas;   a circulation system for circulating air downwardly through the clean room;   one or more fan filter units located above the one or more work areas, each fan filter unit comprising: a unit casing;   a ventilation fan housed in said unit casing;   a dust removal filter in the bottom of said unit casing; and   one or more gas absorption filters for removing gases from said circulating air, said one or more gas absorption filters being above said dust removal filter and below said ventilation fan;     an air intake for said ventilation fan located in an upper face of said unit casing;   inspection openings located in said upper face of said unit casing for removing said one or more gas absorption filters from said unit casing and for inserting said one or more gas absorption filters into said unit casing; and   covers for said inspection openings.   
     
     
       9. The clean room according to claim 8, wherein said one or more gas absorption filters are placed side by side on said dust removal filter, said inspection openings are separated by said air intake for said ventilation fan, and the number, size, and location of said inspection openings correspond to the number, size, and location of said one or more gas absorption filters. 
     
     
       10. A fan filter unit for use in filtering air circulating in a clean room, the fan filter unit comprising: a plurality of fan filter subunits, each fan filter subunit comprising a unit casing, a ventilation fan housed in said unit casing, and a dust removal filter in the bottom of said unit casing;   a chamber enclosing the intake sides of said plurality of fan filter subunits, said chamber containing one or more air intake openings common to said plurality of fan filter subunits; and   a gas absorption filter for removing gases from said circulating air disposed in each of said one or more air intake openings of said chamber.   
     
     
       11. The fan filter unit of claim 10, wherein each of said one or more gas absorption filters is selected from the group consisting of an alkaline gas absorption filter, an acidic gas absorption filter, and an organic gas absorption filter. 
     
     
       12. A vertical laminar-flow type clean room, comprising: one or more work areas;   a circulation system for circulating air downwardly through the clean room;   one or more fan filter units located above the one or more work areas, at least one of said fan filter units comprising: a plurality of fan filter subunits, each fan filter subunit comprising a unit casing, a ventilation fan housed in said unit casing, and a dust removal filter in the bottom of said unit casing;   a chamber enclosing the intake sides of said plurality of fan filter subunits, said chamber containing one or more air intake openings common to said plurality of fan filter subunits; and   a gas absorption filter for removing gases from said circulating air disposed in each of said one or more air intake openings of said chamber.     
     
     
       13. The fan filter unit of claim 12, wherein each of said one or more gas absorption filters is selected from the group consisting of an alkaline gas absorption filter, an acidic gas absorption filter, and an organic gas absorption filter.